1. Field of the Invention
The present invention relates to a thermal poling method, piezoelectric film and manufacturing method of same, thermal poling apparatus, and inspection method of piezoelectric property.
2. Description of the Related Art
FIG. 11 is a schematic diagram illustrating a conventional poling apparatus.
A crystal 33 is sandwiched in the center of a pair of electrodes 35 constituted of two parallel flat plates each having 10×10 mm2 so that an electric field is applied in the direction not subjected to mechanical poling. In addition, the crystal 33 together with the electrodes 35 is immersed in an oil 36 of an oil bath 37, and the oil 36 in which the crystal 33 has been immersed is then heated to 125° C. by a heater 38. After having reached a specified temperature of the oil, a DC electric field of 1 kV/cm is applied between the electrodes 35 for 10 hours via lead wires 40 from a high-voltage power supply 39. Therefore, the crystal 33 is subjected to a poling treatment (for example, refer to Patent Literature 1).
[Patent Literature 1] Japanese Patent Laid-Open No. 10-177194 (Paragraph 0018, FIG. 4)